/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package bdhub.littletail.lib.net.volley.toolbox;

import org.apache.http.impl.cookie.DateParseException;
import org.apache.http.impl.cookie.DateUtils;
import org.apache.http.protocol.HTTP;

import java.util.Map;

import bdhub.littletail.lib.net.volley.Cache;
import bdhub.littletail.lib.net.volley.NetworkResponse;

/**
 * Utility methods for parsing HTTP headers.
 */
public class HttpHeaderParser {
	
	/**
	 * 缓存有效期设置为一个月（其实每次读缓存时都会向服务器更新，这里是指超过一个月都没读过缓存，以后也不读这个缓存，直接向服务器读取数据）
	 */
	private static final long CUSTOM_TTL = 30l * 24 * 60 * 60 * 1000;

    /**
     * Extracts a {@link Cache.Entry} from a {@link NetworkResponse}.
     *
     * @param response The network response to parse headers from
     * @return a cache entry for the given response, or null if the response is not cacheable.
     */
    public static Cache.Entry parseCacheHeaders(NetworkResponse response) {
//        long now = System.currentTimeMillis();
//
//        Map<String, String> headers = response.headers;
//
//        long serverDate = 0;
//        long serverExpires = 0;
//        long softExpire = 0;
//        long maxAge = 0;
//        boolean hasCacheControl = false;
//
//        String serverEtag = null;
//        String headerValue;
//
//        headerValue = headers.get("Date");
//        if (headerValue != null) {
//            serverDate = parseDateAsEpoch(headerValue);
//        }
//
//        headerValue = headers.get("Cache-Control");
//        if (headerValue != null) {
//            hasCacheControl = true;
//            String[] tokens = headerValue.split(",");
//            for (int i = 0; i < tokens.length; i++) {
//                String token = tokens[i].trim();
//                if (token.equals("no-cache") || token.equals("no-store")) {
//                    return null;
//                } else if (token.startsWith("max-age=")) {
//                    try {
//                        maxAge = Long.parseLong(token.substring(8));
//                    } catch (Exception e) {
//                    }
//                } else if (token.equals("must-revalidate") || token.equals("proxy-revalidate")) {
//                    maxAge = 0;
//                }
//            }
//        }
//
//        headerValue = headers.get("Expires");
//        if (headerValue != null) {
//            serverExpires = parseDateAsEpoch(headerValue);
//        }
//
//        serverEtag = headers.get("ETag");
//
//        // Cache-Control takes precedence over an Expires header, even if both exist and Expires
//        // is more restrictive.
//        if (hasCacheControl) {
//            softExpire = now + maxAge * 1000;
//        } else if (serverDate > 0 && serverExpires >= serverDate) {
//            // Default semantic for Expire header in HTTP specification is softExpire.
//            softExpire = now + (serverExpires - serverDate);
//        }
//
//        Cache.Entry entry = new Cache.Entry();
//        entry.data = response.data;
//        entry.etag = serverEtag;
//        entry.softTtl = softExpire;
//        entry.ttl = entry.softTtl;
//        entry.serverDate = serverDate;
//        entry.responseHeaders = headers;
        
    	/**
    	 * 我们的服务器现在没有做 header 的缓存控制<br />
    	 * 现在在这里写死控制逻辑：<br />
    	 * 1、设置默认的缓存时间（ttl）。<br />
    	 * 2、每次请求时，都向服务器拉取数据更新缓存（softTtl 控制）。
    	 * 
    	 * Even 2015-1-10
    	 */
        Cache.Entry entry = new Cache.Entry();
        entry.data = response.data;
        //entry.etag = serverEtag;
        entry.softTtl = 0;
        entry.ttl = System.currentTimeMillis() + CUSTOM_TTL;
        //entry.serverDate = serverDate;
        entry.responseHeaders = response.headers;

        return entry;
    }

    /**
     * Parse date in RFC1123 format, and return its value as epoch
     */
    public static long parseDateAsEpoch(String dateStr) {
        try {
            // Parse date in RFC1123 format if this header contains one
            return DateUtils.parseDate(dateStr).getTime();
        } catch (DateParseException e) {
            // Date in invalid format, fallback to 0
            return 0;
        }
    }

    /**
     * Returns the charset specified in the Content-Type of this header,
     * or the HTTP default (ISO-8859-1) if none can be found.
     */
    public static String parseCharset(Map<String, String> headers) {
        String contentType = headers.get(HTTP.CONTENT_TYPE);
        if (contentType != null) {
            String[] params = contentType.split(";");
            for (int i = 1; i < params.length; i++) {
                String[] pair = params[i].trim().split("=");
                if (pair.length == 2) {
                    if (pair[0].equals("charset")) {
                        return pair[1];
                    }
                }
            }
        }

        return HTTP.DEFAULT_CONTENT_CHARSET;
    }
}
